Needle path planning and needle guidance are used in non-invasive surgical procedures in order to avoid critical structure and reduce tissue trauma. During needle path planning DynaCT is used to establish the needle path, and during needle guidance, real time fluoroscopy is used to guide the needle to a target location. Fluoroscopic images and DynaCT are generated using X-rays which are a form of ionizing radiation. To prevent adverse effects from exposure to ionizing radiation the dose is typically managed by restricting the use of these modalities in duration, frequency and space.
Currently, conventional systems achieve a reduction of spatial ionizing radiation dose by allowing for manual alteration of collimator positions by a user. The user is required to identify a particular region of a patient's body and then manually adjust the collimators so that an x-ray image of that particular region will be properly acquired. Such an approach is time consuming, dependent on the user and disruptive to the clinical workflow.
A wide variety of collimators are available, such as collimators with rectangular panels, leaf collimators and semi-transparent collimators. Each type of collimator provides a varying degree of freedom with regard to optimal collimation. Greater flexibility in collimation provides the advantages of being able to reduce the dose of spatial ionizing radiation to which a patient is exposed while acquiring an x-ray image of a particular region of the patient's body. However, greater flexibility in collimation is also accompanied by a complexity in operating the collimators, which decreases the usability of the overall system.